Unistrut channels for forming a variety of structures are well known.
The Unistrut system employs channel sections made exclusively of steel which vary only in overall profile height and the thickness of the steel used. Each Unistrut channel in practice is available alone or welded to one or more pieces of the same section in various arrangements or to thin continuous steel plate to present a varied range of steel structural profiles to which blind connections can be made using Unistrut nuts and screws.
A range of flat and folded, pre-drilled steel plates are available with the Unistrut system to connect channels together in different ways to create frame structures.
Fittings are also available so that channels can provide support for cable trays or pipes.
Unistrut channels are generally left open between connections although a flat faced closure strip is available. This is the only continuous section that is available to Unistrut channels but is not itself channel shaped and is not used to make connections.
Unistrut channels are also used to create truss frames and space frames to which blind attachments can be made.
While the Unistrut system is used to make frames and not continuous surfaces it can be used to provide support for them.
Unistrut nuts only fit a range of Unistrut channels which are available in appropriate shapes and are too rigid to be made to enclose another profile.
A problem with the Unistrut system is its limited use in terms of the structures that can be produced in practice for the reasons explained above.